Booster device



Nov. 15, 1966 J. F. HAMILTON BOOSTER DEVICE Filed May 20, 1965 NOE JOHN F. HAMILTON mwgm 12.

AGENT United States Patent 3,285,173 BOOSTER DEVICE John F. Hamilton, San Antonio, Tex., assignor to Hercules Incorporated, a corporation of Delaware Filed May 20, 1965, Ser. No. 457,263 The portion of the term of the patent subsequent to May 25, 1982, has been disclaimed Claims. (Cl. 102-24) This application is a continuation-in-part of my copending application Serial No. 337,090, filed January 10, 1964, now Patent No. 3,185,092.

This invention relates to booster devices and more particularly to a cap-sensitive booster device which is designed to be interconnected with compatible cap-insensitive explosive cartridges having protrusion means and yieldable seals to form a compressed explosive column assembly such as disclosed in my aboveddentified copending application.

The primary object of the present invention is to provide a booster device for the above-mentioned service which is simple in construction, economical to manufacture, uniformly reliable and capable of being interconnected in the explosive column assembly in a facile manner with retention of the feature of the compressed explosive column assembly.

Other objects will appear hereinafter, the novel features being set forth in the appended claims.

In accordance with the present invention, there is provided a cap-sensitive booster device which is designed to be interconnected with compatible cap-insensitive explosive cartridges having protrusion means and yieldable seals to form a compressed explosive column assembly, said device comprising a thin-wall substantially cylindrical plastic container having an externally threaded male coupling and end closure on one end thereof and having an internally threaded female coupling on the other end thereof, a longitudinal slot extending along the length of the male coupling to adjacent the female coupling, a cap-sensitive explosive charge disposed within the container from the end closure to adjacent the female coupling, a coaxially positioned cap well extending through the end closure and into the explosive charge, said cap well being adapted to fully accommodate an electric blasting cap and said longitudinal slot being adapted to accommodate the leg wires thereof, and the end closure of said male coupling having protrusion means to contact and to force the yieldable seal of a compatible cap-insensitive explosive cartridge into the explosive adjacent thereto.

For a more complete understanding of the present invention andfor further objects and advantages thereof, reference is now made to the accompanying drawing wherein reference symbols refer to like parts wherever they occur.

FIGURE 1 is a side view of a booster device in accordance with the present invention;

FIGURE 2 is an end view of the booster device depicted in FIGURE 1; and

FIGURE 3 is a sectional view of the booster device taken along line 33 of FIGURE 1.

With reference to the drawings, a thin-wall elongated blown plastic container 1 has a cast cap-sensitive explosive 2 disposed therein throughout about half the length of the container. A coaxially positioned cap well 3 extends into the explosive 2. A double lead externally threaded male coupling 4 with a rounded thread and standard pitch of 29 and a convex end closure 5 are formed as a unitary structure in the thin wall at one end of the container 1, and the explosive 2 extends throughout the length of the coupling. An internally 3,285,173 Patented Nov. 15, 1966 threaded female coupling 6 with threads compatible with the male coupling is formed in the thin wall on the other end of the container 1 and extends substantially to the explosive 2. The male coupling 4 has a reduced external diameter relative to the internal diameter of the female coupling 6 with a transition taper 7 being provided in the thin wall of the container 1 to accomplish this. The relationship between the diameters of the couplings is such as to insure a snug and yet easily rotatable threading. The threaded female coupling 6 has double lead internal threads 8 positioned in the midportion of the coupling. This arrangement facilitates the insertion of the male coupling of a compatible carp-insensitive explosive cartridge since the unthreaded extending portion of the coupling 6 serves as a guiding sleeve for proper engagement of the threaded couplings and adds rigidity to an explosive column assembly of the booster and associated cartridges. The arrangement also reduces the number of turns required for interconnection of the booster in the assembly, and a longitudinal slot 10 extending along the length of the male coupling 4 to adjacent the female coupling 6 accommodates and protects the leg wires of an E. B. cap within the cap well 3 during interconnection of the booster to a compatible cap-insensitive cartridge.

Referring now particularly to FIGURE 1, it will be appreciated that a considerable bending moment can occur in the booster coupling 6 particularly when several can tridges are interconnected in a horizontal position and then lifted for insertion in a vertical borehole. Accordingly, eight equally spaced reinforcing fillets 9 are provided which extend across the threads 8. Furthermore, the threaded portion of the male coupling 4 is greater than the threaded portion of the female coupling 6 to insure that in threadedly assembling the booster 1 in a column of cap-insensitive cartridges, the convex end closure 5 of the male coupling exerts a positive compressive force on the yieldable seal and adjacent explosive of the female coupling of a compatible cartridge. If the cartridged explosive is soft, the yieldable seal will be depressed therein 'by the booster coupling. If the cartridged explosive is hard, there will be very little depression, if any, of the yield-able seal. In any (Went, regardless of the exact height to which the cartridges are filled, including vagaries in filling height during manufacture and possible subsequent shrinkage, a compensating adjustment insuring minimum proximity of explosive charges is actually made in the field during assembly of cartridges with the booster of this invention by the exertion of the compressive force heretofore discussed. This insures a consistent propagating relationship with consistency of rate and quite advantageously is accomplished in the field at the time the explosive column assembly with the booster is being readied for use.

The following example will serve to illustrate a commercially sized preferred embodiment of this invention. It is to be understood, however, that the scope of the invention is not limited thereby with respect to the specific structure or to the explosive charges utilized.

A series of thin-wall containers was formed by blowmolding high-density polyethylene having a density of 0.962 and a nominal melt index of 0.5 (I at C.). These containers were molded in a split mold designed to yield the structure heretofore described and illustrated as a preferred embodiment of the invention. Dimensions of the containers were 8%" overall length, 2 body diameter, male coupling 4%" long, threaded portion of male coupling 2 /2" along with a convex end closure extending and with one rounded thread per 1" with double lead, said thread having a root diameter of 2 /8" and external diameter of 2 /2", and a female coupling 4 long, threaded midportion of female coupling /2 c. to c. of split double lead thread wide and deep with four fillets each side. The longitudinal slot for the leg wires was A" wide and /2" deep at the end closure and was tapered along the length of the male coupling to become flush adjacent the fem-ale coupling. The wall thickness of the body of the container, including the female coupling, was approximately 40 mils, and the wall thickness of the male coupling was approximately 55 mils.

Each of these containers was charged with cast pentolite (50% TNT and 50% PETN) with the cap well formed therein by a removable core. The cap well had a diameter of 6 and extended into the container 2%". The charge extended from the end closure to adjacent the female coupling or the length of the male coupling, which was about 4 /8" and weighed about 500 grams. No seal was necessary adjacent the female coupling in view of the rigid cast p'entolite. The booster devices thus manufactured were tested and found to detonate with a No. 6 EB. cap after storage in water at 300 p.s.i. for seven days. Furthermore, the boosters thus manufactured were tested and initiated under conventional field conditions in explosive column assemblies containing conventional cap-insensitive explosives. The tests were satisfactory in all respects with additional advantages hereinafter set forth.

With reference to the foregoing, it will be appreciated that the containers of this invention may be formed in various sizes from many of the plastic materials capable of being blown but that the economy of the material will largely dictate its use. Thus, although linear polyethylene is preferred and has been found highly satisfactory, polyolefins generally, and copolymers and alloys thereof and otherpmaterials such as ABS terpolymer, plasticized or rigid -poly(vinyl chloride), plasticized vinyl chloride-vinyl acetate copolymer and the like may be used. Also, it will be appreciated that in addition to the specific explosive used in the example, other cap-sensitive explosives of various types including rigid and nonrigid compositions may be used such as generally, composition B (59.5% cyclonite, 39.5% TNT, 1.0% wax), gelatins, dynamites and the like. It will be appreciated, however, that in using nonrigid compositions, a liner for the cap well and a seal to retain the explosive charge are necessary and are contemplated within the purview of the invention. Since the adaptation of these element-s is well understood in the art, they are not further defined except to state that when seals are utilized, it is highly preferable that they be of the yieldable type such as disclosed in my aforementioned copending application. Also, it will be appreciated that the leg wire slot may be indented to extend across the end closure and intersect the cap well. However, the booster device as presented herein affords an additional marginal advantage by compressing the leg wires between the end closure and the seal of an interconnected cartridge thus snubbing the leg wires and affording additional protection against the possibility of pulling them from the cap under unusual or accidental circumstances.

From the foregoing, it will be evident to those skilled in the art that various modifications can be made or followed, in the light of the foregoing disclosure and discussion, without departing from the spirit or scope of the disclosure or from the scope of the claims.

What I claim and desire to protect by Letters Patent is:

1. A cap-sensitive booster device which is designed to be interconnected with compatible cap-insensitive explosive cartridges having protrusion means and yieldable seals to form a compressed explosive column assembly, said device comprising:

(a) a thin-wall substantially cylindrical plastic container having an externally threaded male coupling and end closure on one end thereof and having an internally threaded female coupling on the other end thereof,

(b) a longitudinal slot extending along the length of the male coupling to adjacent the female coupling, said longitudinal slot being tapered along the length of the male coupling to become flush adjacent the female coupling,

(0) a cap-sensitive explosive charge disposed within the container from the end closure to adjacent the female coupling,

((1) a coaxially positioned cap well extending through the end closure and into the explosive charge, said cap well being adapted to fully accommodate an electric blasting cap and said longitudinal slot being adapted to accommodate the leg wires thereof, and

(e) the end closure of said male coupling having protrusion means to contact and to force the yieldable seal of a compatible cap-insensitive explosive cartridge into the explosive adjacent thereto.

2. The booster deviceaccording to claim 1 wherein the female coupling has a threaded midportion only with at least four equally spaced reinforcing fillets for each complete turn thereof extending across the threads.

3. The booster device according to claim 1 wherein the cap-sensitive explosive charge is cast pentolite.

4. The booster device according to claim 1 wherein the end closure of said male coupling is convex.

5. The booster device according to claim 1 wherein the plastic container is high density polyethylene.

References Cited by the Examiner UNITED STATES PATENTS 2,755,735 7/1956 Harter 1O2-24 3,058,419 10/1962 OBrieri 10'2-24 3,082,689 3/1963 Grifiith et al 10224 3,185,092 5/1965 Hamilton 102-24 FOREIGN PATENTS 1,125,984 7/ 1956 France.

SAMUEL FEINBERG, Primary Examiner. BENJAMIN A. BORCHELT, Examiner.

R. V. LOTTMANN, V. R. PENDEGRASS,

Assistant Examiners. 

1. A CAP-SENSITIVE BOOSTER DEVICE WHICH IS DESIGNED TO BE INTERCONNECTED WITH COMPATIBLE CAP-INSENSITIVE EXPLOSIVE CARTRIDGE HAVING PROTRUSION MEANS AND YIELDABLE SEALS TO FORM A COMPRESSED EXPLOSIVE COLUMN ASSEMBLY, SAID DEVICE COMPRISING: (A) A THIN-WALL SUBSTANTIALLY CYLINDRICAL PLASTIC CONTAINER HAVING AN EXTERNALLY THREADED MALE COUPLING AND END CLOSURE ON ONE END THEREOF AND HAVING AN INTERNALLY THREADED FEMALE COUPLING ON THE OTHER END THEREOF, (B) A LONGITUDINAL SLOT EXTENDING ALONG THE LENGTH OF THE MALE COUPLING TO ADJACENT THE FEMALE COUPLING, SAID LONGITUDINAL SLOT BEING TAPERED ALONG THE LENGTH OF THE MALE COUPLING TO BECOME FLUSH ADJACENT THE FEMALE COUPLING, (C) A CAP-SENSITIVE EXPLOSIVE CHARGE DISPOSED WITHIN THE CONTAINER FROM THE END CLOSURE ADJACENT THE FEMALE COUPLING, (D) A COAXIALLY POSITIONED CAP WELL EXTENDING THROUGH THE END CLOSURE AND INTO THE EXPLOSIVE CHARGE, SAID CAP WELL BEING ADAPTED TO FULLY ACCOMODATE AN ELECTRIC BLASTING CAP AND SAID LONGITUDINAL SLOT BEING ADAPTED TO ACCOMODATE THE LEG WIRES THEREOF, AND (E) THE END CLOSURE OF SAID MALE COUPLING HAVING PROTRUSION MEANS TO CONTACT AND TO FORCE THE YIELDABLE SEAL TO A COMPATIBLE CAP-SENSITIVE EXPLOSIVE CARTRIDGE INTO THE EXPLOSIVE ADJACENT THERETO. 